U.S. patent number 8,968,142 [Application Number 13/897,668] was granted by the patent office on 2015-03-03 for multi-speed transmission.
This patent grant is currently assigned to Ford Global Technologies, LLC. The grantee listed for this patent is Ford Global Technologies, LLC. Invention is credited to Robert Scott Lippert.
United States Patent |
8,968,142 |
Lippert |
March 3, 2015 |
Multi-speed transmission
Abstract
A transmission gearing arrangement produces nine forward speed
ratios and one reverse speed ratio by selective engagement of three
shift elements in various combinations. Some embodiment includes
four simple planetary gear sets and six shift elements of which one
is a brake. Another embodiment includes two axis transfer gear
pairs in place of one of the planetary gear sets.
Inventors: |
Lippert; Robert Scott (Ann
Arbor, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Global Technologies, LLC
(Dearborn, MI)
|
Family
ID: |
51831552 |
Appl.
No.: |
13/897,668 |
Filed: |
May 20, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140342870 A1 |
Nov 20, 2014 |
|
Current U.S.
Class: |
475/275; 475/296;
475/317; 475/330 |
Current CPC
Class: |
F16H
3/66 (20130101); F16H 3/62 (20130101); F16H
2200/2012 (20130101); F16H 2200/201 (20130101); F16H
2200/0065 (20130101); F16H 2200/2046 (20130101); F16H
2200/2097 (20130101) |
Current International
Class: |
F16H
3/62 (20060101); F16H 3/44 (20060101); F16H
37/06 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
H Benford, M. Leising, The Lever Analogy: A New Tool in
Transmission Analysis, 1982, Society of Automotive Engineers, Inc.
810102, p. 429-437. cited by applicant.
|
Primary Examiner: Le; David D
Assistant Examiner: Hannon; Timothy
Attorney, Agent or Firm: Dottavio; James Brooks Kushman
P.C.
Claims
What is claimed is:
1. A transmission comprising: a first gearing arrangement which
continuously fixedly constrains a first shaft to rotate faster than
an input shaft and in a same direction; a second gearing
arrangement which selectively imposes a linear speed relationship
in order of a second shaft, the input shaft, and an output shaft;
and a third gearing arrangement which fixedly imposes a linear
speed relationship in order of a third shaft, the output shaft, and
a fourth shaft.
2. The transmission of claim 1, wherein the first gearing
arrangement comprises: a first simple planetary gear set having a
first sun gear fixedly coupled to a transmission housing, a first
ring gear fixedly coupled to the first shaft, a first planet
carrier fixedly coupled to the input shaft, and at least one planet
gear supported for rotation on the first planet carrier and in
continuous meshing engagement with the first sun gear and the first
ring gear.
3. The transmission of claim 1, wherein the second gearing
arrangement comprises: a second simple planetary gear set having a
second sun gear, a second ring gear fixedly coupled to the output
shaft, a second planet carrier fixedly coupled to the input shaft,
and at least one planet gear supported for rotation on the second
planet carrier and in continuous meshing engagement with the second
sun gear and the second ring gear; and a first clutch configured to
selectively couple the second sun gear to the second shaft.
4. The transmission of claim 1, wherein the second gearing
arrangement comprises: a second simple planetary gear set having a
second sun gear, a second ring gear fixedly coupled to the output
shaft, a second planet carrier fixedly coupled to the input shaft,
and at least one planet gear supported for rotation on the second
planet carrier and in continuous meshing engagement with the second
sun gear and the second ring gear; and a first clutch configured to
selectively couple the second ring gear to the output shaft.
5. The transmission of claim 1, wherein the third gearing
arrangement comprises: a third simple planetary gear set having a
third sun gear fixedly coupled to the third shaft, a third ring
gear fixedly coupled to the fourth shaft, a third planet carrier
fixedly coupled to the output shaft, and at least one planet gear
supported for rotation on the third planet carrier and in
continuous meshing engagement with the third sun gear and the third
ring gear.
6. The transmission of claim 1, further comprising: a brake
configured to selectively hold the fourth shaft against rotation; a
second clutch configured to selectively couple the third shaft to
the input shaft; a third clutch configured to selectively couple
the first shaft to the second shaft; and a fourth clutch configured
to selectively couple the second shaft to the fourth shaft.
7. The transmission of claim 1, further comprising: a fourth
gearing arrangement which selectively imposes a linear speed
relationship in order of the first shaft, the second shaft, and the
third shaft.
8. The transmission of claim 7, wherein the fourth gearing
arrangement comprises: a fourth simple planetary gear set having a
fourth sun gear, a fourth ring gear fixedly connected to the third
shaft, a fourth planet carrier fixedly coupled to the second shaft,
and at least one planet gear supported for rotation on the fourth
planet carrier and in continuous meshing engagement with the fourth
sun gear and the fourth ring gear; and a fifth clutch configured to
selectively couple the fourth sun gear to the first shaft.
9. The transmission of claim 7, wherein the fourth gearing
arrangement comprises: a fourth simple planetary gear set having a
fourth sun gear fixedly coupled to the first shaft, a fourth ring
gear, a fourth planet carrier fixedly coupled to the second shaft,
and at least one planet gear supported for rotation on the fourth
planet carrier and in continuous meshing engagement with the fourth
sun gear and the fourth ring gear; and a fifth clutch configured to
selectively couple the fourth ring gear to the third shaft.
10. The transmission of claim 1, wherein the first gearing
arrangement comprises: a layshaft substantially parallel to the
input shaft; a first axis transfer gear coupled to the input shaft;
a second axis transfer gear coupled to the layshaft and in
continuous meshing engagement with the first axis transfer gear; a
third axis transfer gear coupled to the first shaft; and a fourth
axis transfer gear coupled to the layshaft and in continuous
meshing engagement with the third axis transfer gear.
11. The transmission of claim 10, further comprising: a third
clutch configured to selectively couple the layshaft to the second
shaft.
12. The transmission of claim 10, further comprising: a fourth
simple planetary gear set having a fourth sun gear fixedly coupled
to the first shaft, a fourth ring gear, a fourth planet carrier
fixedly coupled to the second shaft, and at least one planet gear
supported for rotation on the fourth planet carrier and in
continuous meshing engagement with the fourth sun gear and the
fourth ring gear; and a fifth clutch configured to selectively
couple the fourth sun gear to the layshaft.
13. A transmission comprising: an input shaft; an output shaft;
first, second, third, and fourth shafts; a gearing arrangement
which fixedly constrains the first shaft to rotate faster than the
input shaft and in a same direction; a first simple planetary gear
set having a first sun gear, a first ring gear, a first planet
carrier fixedly coupled to the second shaft, and at least one
planet gear supported for rotation on the first planet carrier and
in continuous meshing engagement with the first sun gear and the
first ring gear, the first planetary gear set configured to
selectively impose a linear speed relationship between the first
shaft, the second shaft, and the third shaft; a second simple
planetary gear set having a second sun gear, a second ring gear, a
second planet carrier, and at least one planet gear supported for
rotation on the second planet carrier and in continuous meshing
engagement with the second sun gear and the second ring gear, the
second planetary gear set configured to selectively impose a linear
speed relationship between the second shaft, the input shaft, and
the output shaft; a third simple planetary gear set having a third
sun gear fixedly coupled to the third shaft, a third ring gear
fixedly coupled to the fourth shaft, a third planet carrier fixedly
coupled to the output shaft, and at least one planet gear supported
for rotation on the third planet carrier and in continuous meshing
engagement with the third sun gear and the third ring gear; a first
clutch configured to selectively couple the first shaft and the
second shaft; a second clutch configured to selectively couple the
second shaft and the fourth shaft; a third clutch configured to
selectively couple the input shaft and the third shaft; and a brake
configured to selectively hold the fourth shaft against
rotation.
14. The transmission of claim 13, wherein the gearing arrangement
comprises: a fourth simple planetary gear set having a fourth sun
gear fixedly coupled to a transmission housing, a fourth ring gear
fixedly coupled to the first shaft, a fourth planet carrier fixedly
coupled to the input shaft, and at least one planet gear supported
for rotation on the fourth planet carrier and in continuous meshing
engagement with the fourth sun gear and the fourth ring gear.
15. The transmission of claim 14, further comprising a fourth
clutch configured to selectively couple the first sun gear to the
first shaft and a fifth clutch configured to selectively couple the
second sun gear to the second shaft, wherein the first ring gear is
fixedly coupled to the third shaft and the second ring gear is
fixedly coupled to the output shaft.
16. The transmission of claim 14, further comprising a fourth
clutch configured to selectively couple the first ring gear to the
third shaft and a fifth clutch configured to selectively couple the
second sun gear to the second shaft, wherein the first sun gear is
fixedly coupled to the first shaft and the second ring gear is
fixedly coupled to the output shaft.
17. The transmission of claim 14, further comprising a fourth
clutch configured to selectively couple the first sun gear to the
first shaft and a fifth clutch configured to selectively couple the
second ring gear to the output shaft, wherein the second sun gear
is fixedly coupled to the second shaft and the first ring gear is
fixedly coupled to the third shaft.
18. The transmission of claim 13, wherein the first gearing
arrangement comprises: a layshaft substantially parallel to the
input shaft; a first axis transfer gear coupled to the input shaft;
a second axis transfer gear coupled to the layshaft and in
continuous meshing engagement with the first axis transfer gear; a
third axis transfer gear coupled to the first shaft; and a fourth
axis transfer gear coupled to the layshaft and in continuous
meshing engagement with the third axis transfer gear.
19. The transmission of claim 13, further comprising a fourth
clutch configured to selectively couple the first sun gear to the
first shaft and a fifth clutch configured to selectively couple the
second sun gear to the second shaft, wherein the first ring gear is
fixedly coupled to the third shaft and the second ring gear is
fixedly coupled to the output shaft.
Description
TECHNICAL FIELD
This disclosure relates to the field of automatic transmissions for
motor vehicles. More particularly, the disclosure pertains to an
arrangement of gears, clutches, and the interconnections among them
in a power transmission.
BACKGROUND
Many vehicles are used over a wide range of vehicle speeds,
including both forward and reverse movement. Some types of engines,
however, are capable of operating efficiently only within a narrow
range of speeds. Consequently, transmissions capable of efficiently
transmitting power at a variety of speed ratios are frequently
employed. When the vehicle is at low speed, the transmission is
usually operated at a high speed ratio such that it multiplies the
engine torque for improved acceleration. At high vehicle speed,
operating the transmission at a low speed ratio permits an engine
speed associated with quiet, fuel efficient cruising. Typically, a
transmission has a housing mounted to the vehicle structure, an
input shaft driven by an engine crankshaft, and an output shaft
driving the vehicle wheels, often via a differential assembly which
permits the left and right wheel to rotate at slightly different
speeds as the vehicle turns.
SUMMARY OF THE DISCLOSURE
In a first embodiment, a transmission includes first, second, and
third gearing arrangements. The first gearing arrangement fixedly
constrains a first shaft to rotate faster than an input shaft and
in a same direction. The first gearing arrangement may be, for
example, a simple planetary gear set. Alternatively, the first
gearing arrangement may be, as another example, a collection of
axis transfer gears in combination with a clutch. The second
gearing arrangement selectively imposes a linear speed relationship
between a second shaft, the input shaft, and an output shaft. The
second gearing arrangement may be, for example, a simple planetary
gear set in combination with a clutch. The third gearing
arrangement fixedly imposes a linear speed relationship between a
third shaft, the output shaft, and a fourth shaft. The third
gearing arrangement may be, for example, a simple planetary gear
set. The transmission may further comprise a brake and second,
third, and fourth clutches. The transmission may additionally
comprise a fourth gearing arrangement, which may be a simple
planetary gear set in combination with a clutch.
In a second embodiment, a transmission includes a gearing
arrangement and first, second, and third simple planetary gear
sets, first, second, and third clutches, and a brake. The gearing
arrangement fixedly constrains a first shaft to rotate faster than
an input shaft and in a same direction. The first gearing
arrangement may be, for example, a fourth simple planetary gear
set. Alternatively, the gearing arrangement may be, as another
example, a collection of axis transfer gears in combination with a
clutch. The first simple planetary gear set selectively imposes a
linear speed relationship between the first shaft, a second shaft,
and the third shaft. The second simple planetary gear set
selectively imposes a linear speed relationship between the second
shaft, the input shaft, and an output shaft. The third simple
planetary gear set fixedly imposes a linear speed relationship
between a third shaft, the output shaft, and a fourth shaft. The
transmission may further include fourth and fifth clutches.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a first transmission gearing
arrangement.
FIG. 2 is a schematic diagram of a second transmission gearing
arrangement.
FIG. 3 is a schematic diagram of a third transmission gearing
arrangement.
FIG. 4 is a schematic diagram of a fourth transmission gearing
arrangement.
DETAILED DESCRIPTION
Embodiments of the present disclosure are described herein. It is
to be understood, however, that the disclosed embodiments are
merely examples and other embodiments can take various and
alternative forms. The figures are not necessarily to scale; some
features could be exaggerated or minimized to show details of
particular components. Therefore, specific structural and
functional details disclosed herein are not to be interpreted as
limiting, but merely as a representative basis for teaching one
skilled in the art to variously employ the present invention. As
those of ordinary skill in the art will understand, various
features illustrated and described with reference to any one of the
figures can be combined with features illustrated in one or more
other figures to produce embodiments that are not explicitly
illustrated or described. The combinations of features illustrated
provide representative embodiments for typical applications.
Various combinations and modifications of the features consistent
with the teachings of this disclosure, however, could be desired
for particular applications or implementations.
A gearing arrangement is a collection of rotating elements and
shift elements configured to impose specified speed relationships
among the rotating elements. Some speed relationships, called fixed
speed relationships, are imposed regardless of the state of any
shift elements. Other speed relationships, called selective speed
relationships, are imposed only when particular shift elements are
fully engaged. A linear speed relationship exists among an ordered
list of rotating elements when i) the first and last rotating
element in the group are constrained to have the most extreme
speeds, ii) the speeds of the remaining rotating elements are each
constrained to be a weighted average of the first and last rotating
element, and iii) when the speeds of the rotating elements differ,
they are constrained to be in the listed order, either increasing
or decreasing. The speed of an element is positive when the element
rotates in one direction and negative when the element rotates in
the opposite direction. A discrete ratio transmission has a gearing
arrangement that selectively imposes a variety of speed ratios
between an input shaft and an output shaft.
A group of rotating elements are fixedly coupled to one another if
they are constrained to rotate as a unit in all operating
conditions. Rotating elements can be fixedly coupled by spline
connections, welding, press fitting, machining from a common solid,
or other means. Slight variations in rotational displacement
between fixedly coupled elements can occur such as displacement due
to lash or shaft compliance. One or more rotating elements that are
all fixedly coupled to one another may be called a shaft. In
contrast, two rotating elements are selectively coupled by a shift
element when the shift element constrains them to rotate as a unit
whenever it is fully engaged and they are free to rotate at
distinct speeds in at least some other operating condition. A shift
element that holds a rotating element against rotation by
selectively connecting it to the housing is called a brake. A shift
element that selectively couples two or more rotating elements to
one another is called a clutch. Shift elements may be actively
controlled devices such as hydraulically or electrically actuated
clutches or brakes or may be passive devices such as one way
clutches or brakes. Two rotating elements are coupled if they are
either fixedly coupled or selectively coupled.
An example transmission is schematically illustrated in FIG. 1. The
transmission utilizes four simple planetary gear sets 20, 30, 40,
and 50. A planet carrier 32 rotates about a central axis and
supports a set of planet gears 34 such that the planet gears rotate
with respect to the planet carrier. External gear teeth on the
planet gears mesh with external gear teeth on a sun gear 36 and
with internal gear teeth on a ring gear 38. The sun gear and ring
gear are supported to rotate about the same axis as the carrier.
Gear sets 20, 40, and 50 are similarly structured.
A simple planetary gear set is a type of gearing arrangement that
imposes a fixed linear speed relationship among the sun gear, the
planet carrier, and the ring gear. Other known types of gearing
arrangements also impose a fixed linear speed relationship among
three rotating elements. For example, a double pinion planetary
gear set imposes a fixed linear speed relationship between the sun
gear, the ring gear, and the planet carrier.
A suggested ratio of gear teeth for each planetary gear set is
listed in Table 1.
TABLE-US-00001 TABLE 1 Ring 28/Sun 26 1.729 Ring 38/Sun 36 1.624
Ring 48/Sun 46 2.274 Ring 58/Sun 56 3.430
In the transmission of FIG. 1, input shaft 10 is fixedly coupled to
carrier 22 and carrier 42 and selectively coupled to intermediate
shaft 74 by clutch 68. Intermediate shaft 74 is fixedly coupled to
ring gear 38 and sun gear 56. Output shaft 12 is fixedly coupled to
carrier 52 and ring gear 48. Sun gear 26 is fixedly held against
rotation. Sun gear 36 is selectively coupled to ring gear 28 by
clutch 60. Carrier 32 is selectively coupled to ring gear 28 by
clutch 62, to ring gear 58 by clutch 64, and to sun gear 46 by
clutch 66. Ring gear 58 is selectively held against rotation by
brake 70.
Various combinations of gear sets, clutches, and brakes selectively
impose particular speed relationships. Gear set 20 fixedly imposes
an overdrive relationship between carrier 22 and ring gear 28. In
other words, ring gear 28 is constrained to rotate faster than
carrier 22 and in the same direction in all operating conditions.
The combination of gear set 40 and clutch 66 selectively imposes
various speed relationships between carrier 32, input shaft 10, and
output shaft 12. Engaging clutch 66 couples sun gear 46 to carrier
32 and imposes a linear speed relationship between carrier 32,
input shaft 10, and output shaft 12. Gear set 50 fixedly imposes a
linear speed relationship between sun gear 56, output shaft 12, and
ring gear 58. The combination of gear set 30 and clutches 60, 62,
64, and 66 selectively imposes various speed relationships between
ring gear 28, carrier 32, and sun gear 56. Engaging clutch 60
couples sun gear 36 to ring gear 28 and, in combination with
engaging at least one of clutches 62, 64, and 66, imposes a linear
speed relationship between ring gear 28, carrier 32, and sun gear
56.
As shown in Table 2, engaging the shift elements in combinations of
three establishes nine forward speed ratios and one reverse speed
ratio between input shaft 10 and output shaft 12. An X indicates
that the shift element is required to establish the speed ratio.
When the gear sets have tooth number ratios as indicated in Table
1, the speed ratios have the values indicated in Table 2.
TABLE-US-00002 TABLE 2 60 62 64 66 68 70 Ratio Step Rev. X X X
-4.558 103% 1.sup.st X X X 4.430 2.sup.nd X X X 2.807 1.58 3.sup.rd
X X X 1.877 1.50 4.sup.th X X X 1.341 1.40 5.sup.th X X X 1.107
1.21 6.sup.th X X X 1.000 1.11 7.sup.th X X X 0.854 1.17 8.sup.th X
X X 0.691 1.24 9.sup.th X X X 0.634 1.09
When the driver selects drive (forward), the transmission is
prepared for vehicle launch in 1st by engaging clutches 60 and 68
and brake 70. A shift to 2nd may be accomplished by gradually
disengaging clutch 68 while gradually engaging clutch 62.
Additional upshifts are accomplished according to Table 2. When the
driver selects reverse, the transmission is prepared for vehicle
launch in reverse by engaging clutches 60 and 64 and brake 70.
A second example transmission is illustrated in FIG. 2. This
transmission utilizes four simple planetary gear sets with
suggested tooth number ratios as shown in Table 1. In this
transmission, input shaft 10 is fixedly coupled to carrier 22 and
carrier 42 and selectively coupled to intermediate shaft 74 by
clutch 68. Intermediate shaft 74 is fixedly coupled to sun gear 56
and selectively coupled to ring gear 38 by clutch 60'. Output shaft
12 is fixedly coupled to carrier 52 and ring gear 48. Sun gear 26
is fixedly held against rotation. Sun gear 36 is fixedly coupled to
ring gear 28. Carrier 32 is selectively coupled to ring gear 28 by
clutch 62, to ring gear 58 by clutch 64, and to sun gear 46 by
clutch 66. Ring gear 58 is selectively held against rotation by
brake 70. The transmission of FIG. 2 is operated in the same
fashion as the transmission of FIG. 1.
Various combinations of gear sets, clutches, and brakes selectively
impose particular speed relationships. Gear set 20 fixedly imposes
an overdrive relationship between carrier 22 and ring gear 28. In
other words, ring gear 28 is constrained to rotate faster than
carrier 22 and in the same direction in all operating conditions.
The combination of gear set 40 and clutch 66 selectively imposes
various speed relationships between carrier 32, input shaft 10, and
output shaft 12. Engaging clutch 66 couples sun gear 46 to carrier
32 and imposes a linear speed relationship between carrier 32,
input shaft 10, and output shaft 12. Gear set 50 fixedly imposes a
linear speed relationship between sun gear 56, output shaft 12, and
ring gear 58. The combination of gear set 30 and clutches 60', 62,
64, and 66 selectively imposes various speed relationships between
ring gear 28, carrier 32, and sun gear 56. Engaging clutch 60'
couples ring gear 38 to intermediate shaft 74 and, in combination
with engaging at least one of clutches 62, 64, and 66, imposes a
linear speed relationship between ring gear 28, carrier 32, and sun
gear 56.
A third example transmission is illustrated in FIG. 3. This
transmission utilizes four simple planetary gear sets with
suggested tooth number ratios as shown in Table 1. In this
transmission, input shaft 10 is fixedly coupled to carrier 22 and
carrier 42 and selectively coupled to intermediate shaft 74 by
clutch 68. Intermediate shaft 74 is fixedly coupled to ring gear 38
and sun gear 56. Output shaft 12 is fixedly coupled to carrier 52
and selectively coupled to ring gear 48 by clutch 66'. Sun gear 26
is fixedly held against rotation. Sun gear 36 is selectively
coupled to ring gear 28 by clutch 60. Carrier 32 is fixedly coupled
to sun gear 46 and selectively coupled to ring gear 28 by clutch 62
and to ring gear 58 by clutch 64. Ring gear 58 is selectively held
against rotation by brake 70. The transmission of FIG. 3 is
operated in the same fashion as the transmissions of FIGS. 1 and
2.
Various combinations of gear sets, clutches, and brakes selectively
impose particular speed relationships. Gear set 20 fixedly imposes
an overdrive relationship between carrier 22 and ring gear 28. In
other words, ring gear 28 is constrained to rotate faster than
carrier 22 and in the same direction in all operating conditions.
The combination of gear set 40 and clutch 66' selectively imposes
various speed relationships between carrier 32, input shaft 10, and
output shaft 12. Engaging clutch 66' couples ring gear 48 to the
output shaft and imposes a linear speed relationship between
carrier 32, input shaft 10, and output shaft 12. Gear set 50
fixedly imposes a linear speed relationship between sun gear 56,
output shaft 12, and ring gear 58. The combination of gear set 30
and clutches 60, 62, 64, and 66' selectively imposes various speed
relationships between ring gear 28, carrier 32, and sun gear 56.
Engaging clutch 60 couples sun gear 36 to ring gear 28 and, in
combination with engaging at least one of clutches 62, 64, and 66',
imposes a linear speed relationship between ring gear 28, carrier
32, and sun gear 56.
A fourth example transmission is illustrated in FIG. 4. This
transmission utilizes three simple planetary gear sets 30, 40, and
50 with suggested tooth number ratios as indicated in Table 1.
These simple planetary gear sets have a sun gear, a ring gear, and
a carrier that rotate about a central axis. Additionally, axis
transfer gears 82 and 88 are supported for rotation about this
central axis. Gear 82 is radially larger than gear 88. Layshaft 72
is parallel to the central axis but offset from the central axis.
Axis transfer gears 84 and 86 are supported for rotation about the
axis of layshaft 72. Axis transfer gears 84 and 86 continuously
mesh with axis transfer gears 82 and 88 respectively.
Input shaft 10 is fixedly coupled to axis transfer gear 82 and
carrier 42 and selectively coupled to intermediate shaft 74 by
clutch 68. Intermediate shaft 74 is fixedly coupled to ring gear 38
and sun gear 56. Intermediate shaft 76 is fixedly coupled to axis
transfer gear 88. Output shaft 12 is fixedly coupled to carrier 52
and ring gear 48. Sun gear 36 is selectively coupled to
intermediate shaft 76 by clutch 60. Carrier 32 is selectively
coupled to intermediate shaft 76 by clutch 62, to ring gear 58 by
clutch 64, and to sun gear 46 by clutch 66. Ring gear 58 is
selectively held against rotation by brake 70. This arrangement may
be suitable for front wheel drive transmissions in which an axis
transfer from the engine axis to the differential axis is required.
The transmission of FIG. 4 is operated in the same fashion as the
transmissions of FIGS. 1-3.
The combination of axis transfer gears 82, 84, 86, and 88 impose an
overdrive relationship between input shaft 10 and intermediate
shaft 76. In other words, intermediate shaft 76 is constrained to
rotate faster than input shaft 10 and in the same direction. The
combination of gear set 40 and clutch 66 selectively imposes
various speed relationships between carrier 32, input shaft 10, and
output shaft 12. Engaging clutch 66 couples sun gear 46 to carrier
32 and imposes a linear speed relationship between carrier 32,
input shaft 10, and output shaft 12. Gear set 50 fixedly imposes a
linear speed relationship between sun gear 56, output shaft 12, and
ring gear 58. Ring gear 58 may be selectively held against rotation
by engaging or disengaging brake 70. Sun gear 56 may be selectively
constrained to rotate at the same speed as input shaft 10 and in
the same direction by engaging or disengaging clutch 68. The
combination of gear set 30 and clutches 60, 62, 64, and 66
selectively imposes various speed relationships between
intermediate shaft 76, carrier 32, and sun gear 56. Engaging clutch
60 couples sun gear 36 to intermediate shaft 76 and, in combination
with engaging at least one of clutches 62, 64, and 66, imposes a
linear speed relationship between ring gear 28, carrier 32, and sun
gear 56.
While exemplary embodiments are described above, it is not intended
that these embodiments describe all possible forms encompassed by
the claims. The words used in the specification are words of
description rather than limitation, and it is understood that
various changes can be made without departing from the spirit and
scope of the disclosure. As previously described, the features of
various embodiments can be combined to form further embodiments of
the invention that may not be explicitly described or illustrated.
While various embodiments could have been described as providing
advantages or being preferred over other embodiments or prior art
implementations with respect to one or more desired
characteristics, those of ordinary skill in the art recognize that
one or more features or characteristics can be compromised to
achieve desired overall system attributes, which depend on the
specific application and implementation. These attributes can
include, but are not limited to cost, strength, durability, life
cycle cost, marketability, appearance, packaging, size,
serviceability, weight, manufacturability, ease of assembly, etc.
As such, embodiments described as less desirable than other
embodiments or prior art implementations with respect to one or
more characteristics are not outside the scope of the disclosure
and can be desirable for particular applications.
* * * * *